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Hur JY. γ-Secretase in Alzheimer's disease. Exp Mol Med 2022; 54:433-446. [PMID: 35396575 PMCID: PMC9076685 DOI: 10.1038/s12276-022-00754-8] [Citation(s) in RCA: 85] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 01/05/2022] [Accepted: 01/20/2022] [Indexed: 12/16/2022] Open
Abstract
Alzheimer's disease (AD) is caused by synaptic and neuronal loss in the brain. One of the characteristic hallmarks of AD is senile plaques containing amyloid β-peptide (Aβ). Aβ is produced from amyloid precursor protein (APP) by sequential proteolytic cleavages by β-secretase and γ-secretase, and the polymerization of Aβ into amyloid plaques is thought to be a key pathogenic event in AD. Since γ-secretase mediates the final cleavage that liberates Aβ, γ-secretase has been widely studied as a potential drug target for the treatment of AD. γ-Secretase is a transmembrane protein complex containing presenilin, nicastrin, Aph-1, and Pen-2, which are sufficient for γ-secretase activity. γ-Secretase cleaves >140 substrates, including APP and Notch. Previously, γ-secretase inhibitors (GSIs) were shown to cause side effects in clinical trials due to the inhibition of Notch signaling. Therefore, more specific regulation or modulation of γ-secretase is needed. In recent years, γ-secretase modulators (GSMs) have been developed. To modulate γ-secretase and to understand its complex biology, finding the binding sites of GSIs and GSMs on γ-secretase as well as identifying transiently binding γ-secretase modulatory proteins have been of great interest. In this review, decades of findings on γ-secretase in AD are discussed.
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Affiliation(s)
- Ji-Yeun Hur
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA.
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2
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Contino S, Suelves N, Vrancx C, Vadukul DM, Payen VL, Stanga S, Bertrand L, Kienlen-Campard P. Presenilin-Deficient Neurons and Astrocytes Display Normal Mitochondrial Phenotypes. Front Neurosci 2021; 14:586108. [PMID: 33551720 PMCID: PMC7862347 DOI: 10.3389/fnins.2020.586108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 12/14/2020] [Indexed: 01/13/2023] Open
Abstract
Presenilin 1 (PS1) and Presenilin 2 (PS2) are predominantly known as the catalytic subunits of the γ-secretase complex that generates the amyloid-β (Aβ) peptide, the major constituent of the senile plaques found in the brain of Alzheimer's disease (AD) patients. Apart from their role in γ-secretase activity, a growing number of cellular functions have been recently attributed to PSs. Notably, PSs were found to be enriched in mitochondria-associated membranes (MAMs) where mitochondria and endoplasmic reticulum (ER) interact. PS2 was more specifically reported to regulate calcium shuttling between these two organelles by controlling the formation of functional MAMs. We have previously demonstrated in mouse embryonic fibroblasts (MEF) an altered mitochondrial morphology along with reduced mitochondrial respiration and increased glycolysis in PS2-deficient cells (PS2KO). This phenotype was restored by the stable re-expression of human PS2. Still, all these results were obtained in immortalized cells, and one bottom-line question is to know whether these observations hold true in central nervous system (CNS) cells. To that end, we carried out primary cultures of PS1 knockdown (KD), PS2KO, and PS1KD/PS2KO (PSdKO) neurons and astrocytes. They were obtained from the same litter by crossing PS2 heterozygous; PS1 floxed (PS2+/-; PS1flox/flox) animals. Genetic downregulation of PS1 was achieved by lentiviral expression of the Cre recombinase in primary cultures. Strikingly, we did not observe any mitochondrial phenotype in PS1KD, PS2KO, or PSdKO primary cultures in basal conditions. Mitochondrial respiration and membrane potential were similar in all models, as were the glycolytic flux and NAD+/NADH ratio. Likewise, mitochondrial morphology and content was unaltered by PS expression. We further investigated the differences between results we obtained here in primary nerve cells and those previously reported in MEF cell lines by analyzing PS2KO primary fibroblasts. We found no mitochondrial dysfunction in this model, in line with observations in PS2KO primary neurons and astrocytes. Together, our results indicate that the mitochondrial phenotype observed in immortalized PS2-deficient cell lines cannot be extrapolated to primary neurons, astrocytes, and even to primary fibroblasts. The PS-dependent mitochondrial phenotype reported so far might therefore be the consequence of a cell immortalization process and should be critically reconsidered regarding its relevance to AD.
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Affiliation(s)
- Sabrina Contino
- Alzheimer Research Group, Molecular and Cellular Division (CEMO), Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Nuria Suelves
- Alzheimer Research Group, Molecular and Cellular Division (CEMO), Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Céline Vrancx
- Alzheimer Research Group, Molecular and Cellular Division (CEMO), Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Devkee M. Vadukul
- Alzheimer Research Group, Molecular and Cellular Division (CEMO), Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Valery L. Payen
- Laboratory of Advanced Drug Delivery and Biomaterial (ADDB), Louvain Drug Research Institute (LDRI), Université Catholique de Louvain, Brussels, Belgium
| | - Serena Stanga
- Neuroscience Institute Cavalieri Ottolenghi, Department of Neuroscience, University of Torino, Torino, Italy
| | - Luc Bertrand
- Pole of Cardiovascular Research, Institute of Experimental and Clinical Research, Université Catholique de Louvain, Brussels, Belgium
| | - Pascal Kienlen-Campard
- Alzheimer Research Group, Molecular and Cellular Division (CEMO), Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
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3
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GABA-A receptor modulating steroids in acute and chronic stress; relevance for cognition and dementia? Neurobiol Stress 2019; 12:100206. [PMID: 31921942 PMCID: PMC6948369 DOI: 10.1016/j.ynstr.2019.100206] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 11/13/2019] [Accepted: 12/18/2019] [Indexed: 01/10/2023] Open
Abstract
Cognitive dysfunction, dementia and Alzheimer's disease (AD) are increasing as the population worldwide ages. Therapeutics for these conditions is an unmet need. This review focuses on the role of the positive GABA-A receptor modulating steroid allopregnanolone (APα), it's role in underlying mechanisms for impaired cognition and of AD, and to determine options for therapy of AD. On one hand, APα given intermittently promotes neurogenesis, decreases AD-related pathology and improves cognition. On the other, continuous exposure of APα impairs cognition and deteriorates AD pathology. The disparity between these two outcomes led our groups to analyze the mechanisms underlying the difference. We conclude that the effects of APα depend on administration pattern and that chronic slightly increased APα exposure is harmful to cognitive function and worsens AD pathology whereas single administrations with longer intervals improve cognition and decrease AD pathology. These collaborative assessments provide insights for the therapeutic development of APα and APα antagonists for AD and provide a model for cross laboratory collaborations aimed at generating translatable data for human clinical trials.
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Frost GR, Li YM. The role of astrocytes in amyloid production and Alzheimer's disease. Open Biol 2017; 7:170228. [PMID: 29237809 PMCID: PMC5746550 DOI: 10.1098/rsob.170228] [Citation(s) in RCA: 244] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 11/16/2017] [Indexed: 12/18/2022] Open
Abstract
Alzheimer's disease (AD) is marked by the presence of extracellular amyloid beta (Aβ) plaques, intracellular neurofibrillary tangles (NFTs) and gliosis, activated glial cells, in the brain. It is thought that Aβ plaques trigger NFT formation, neuronal cell death, neuroinflammation and gliosis and, ultimately, cognitive impairment. There are increased numbers of reactive astrocytes in AD, which surround amyloid plaques and secrete proinflammatory factors and can phagocytize and break down Aβ. It was thought that neuronal cells were the major source of Aβ. However, mounting evidence suggests that astrocytes may play an additional role in AD by secreting significant quantities of Aβ and contributing to overall amyloid burden in the brain. Astrocytes are the most numerous cell type in the brain, and therefore even minor quantities of amyloid secretion from individual astrocytes could prove to be substantial when taken across the whole brain. Reactive astrocytes have increased levels of the three necessary components for Aβ production: amyloid precursor protein, β-secretase (BACE1) and γ-secretase. The identification of environmental factors, such as neuroinflammation, that promote astrocytic Aβ production, could redefine how we think about developing therapeutics for AD.
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Affiliation(s)
- Georgia R Frost
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
- Programs of Neurosciences, Weill Graduate School of Medical Sciences of Cornell University, New York, NY, USA
| | - Yue-Ming Li
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
- Programs of Neurosciences, Weill Graduate School of Medical Sciences of Cornell University, New York, NY, USA
- Pharmacology, Weill Graduate School of Medical Sciences of Cornell University, New York, NY, USA
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Liu L, Watanabe N, Akatsu H, Nishimura M. Neuronal expression of ILEI/FAM3C and its reduction in Alzheimer's disease. Neuroscience 2016; 330:236-46. [PMID: 27256505 DOI: 10.1016/j.neuroscience.2016.05.050] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 05/20/2016] [Accepted: 05/25/2016] [Indexed: 01/22/2023]
Abstract
Decrease in brain amyloid-β (Aβ) accumulation is a leading strategy for treating Alzheimer's disease (AD). However, the intrinsic mechanism of the regulation of brain Aβ production is largely unknown. Previously, we reported that ILEI (also referred to as FAM3C) binds to the γ-secretase complex and suppresses Aβ production without inhibiting γ-secretase activity. In this study, we examined ILEI expression in mouse brain using immunohistochemistry and subcellular fractionation. Brain ILEI showed widespread expression in neurons and ependymal cells but not in glial and vascular endothelial cells. Neuronal ILEI resided in perinuclear vesicular structures, which were positive for a marker protein of the trans-Golgi network. Although ILEI immunostaining was negative at synaptic terminals, synaptosome fractionation analysis suggested that ILEI was enriched in presynaptic terminals, particularly in the active zone-docked synaptic vesicles. ILEI expression levels in brain peaked during the postnatal period and declined with age. In comparison with age-matched control brains, the number of ILEI-immunoreactive neurons decreased in AD brains, although the subcellular localization was unaltered. Our results suggest that a decline of ILEI expression may cause accumulation of Aβ in the brain and the eventual development of AD.
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Affiliation(s)
- Lei Liu
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan
| | - Naoki Watanabe
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan
| | - Hiroyasu Akatsu
- Choju Medical Institute, Fukushimura Hospital, Toyohashi, Aichi 441-8124, Japan
| | - Masaki Nishimura
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
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Tang W, Tam JHK, Seah C, Chiu J, Tyrer A, Cregan SP, Meakin SO, Pasternak SH. Arf6 controls beta-amyloid production by regulating macropinocytosis of the Amyloid Precursor Protein to lysosomes. Mol Brain 2015; 8:41. [PMID: 26170135 PMCID: PMC4501290 DOI: 10.1186/s13041-015-0129-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 06/11/2015] [Indexed: 11/15/2022] Open
Abstract
Alzheimer’s disease (AD) is characterized by the deposition of Beta-Amyloid (Aβ) peptides in the brain. Aβ peptides are generated by cleavage of the Amyloid Precursor Protein (APP) by the β − and γ − secretase enzymes. Although this process is tightly linked to the internalization of cell surface APP, the compartments responsible are not well defined. We have found that APP can be rapidly internalized from the cell surface to lysosomes, bypassing early and late endosomes. Here we show by confocal microscopy and electron microscopy that this pathway is mediated by macropinocytosis. APP internalization is enhanced by antibody binding/crosslinking of APP suggesting that APP may function as a receptor. Furthermore, a dominant negative mutant of Arf6 blocks direct transport of APP to lysosomes, but does not affect classical endocytosis to endosomes. Arf6 expression increases through the hippocampus with the development of Alzheimer’s disease, being expressed mostly in the CA1 and CA2 regions in normal individuals but spreading through the CA3 and CA4 regions in individuals with pathologically diagnosed AD. Disruption of lysosomal transport of APP reduces both Aβ40 and Aβ42 production by more than 30 %. Our findings suggest that the lysosome is an important site for Aβ production and that altering APP trafficking represents a viable strategy to reduce Aβ production.
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Affiliation(s)
- Weihao Tang
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Physiology and Pharmacology, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
| | - Joshua H K Tam
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Physiology and Pharmacology, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
| | - Claudia Seah
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada.
| | - Justin Chiu
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Physiology and Pharmacology, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
| | - Andrea Tyrer
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Physiology and Pharmacology, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
| | - Sean P Cregan
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Physiology and Pharmacology, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
| | - Susan O Meakin
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Biochemistry, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
| | - Stephen H Pasternak
- J. Allyn Taylor Centre for Cell Biology, Molecular Medicine Research Group, Robarts Research Institute, 1151 Richmond St, London, ON, N6A 5B8, Canada. .,Department of Clinical Neurological Sciences, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada. .,Department of Physiology and Pharmacology, Schulich School of Medicine, the University of Western Ontario, London, ON, N6A 5B7, Canada.
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7
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Lim A, Moussavi Nik SH, Ebrahimie E, Lardelli M. Analysis of nicastrin gene phylogeny and expression in zebrafish. Dev Genes Evol 2015; 225:171-8. [DOI: 10.1007/s00427-015-0500-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 04/24/2015] [Indexed: 11/24/2022]
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Convergence of synapses, endosomes, and prions in the biology of neurodegenerative diseases. Int J Cell Biol 2013; 2013:141083. [PMID: 24307901 PMCID: PMC3838826 DOI: 10.1155/2013/141083] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 09/23/2013] [Indexed: 11/17/2022] Open
Abstract
Age-related misfolding and aggregation of disease-linked proteins in selective brain regions is a characteristic of neurodegenerative diseases. Although neuropathological aggregates that characterize these various diseases are found at sites other than synapses, increasing evidence supports the idea that synapses are where the pathogenesis begins. Understanding these diseases is hampered by our lack of knowledge of what the normal functions of these proteins are and how they are affected by aging. Evidence has supported the idea that neurodegenerative disease-linked proteins have a common propensity for prion protein-like cell-to-cell propagation. However, it is not thought that the prion-like quality of these proteins/peptides that allows their cell-to-cell transmission implies a role for human-to-human spread in common age-related neurodegenerative diseases. It will be important to better understand the molecular and cellular mechanisms governing the role of these aggregating proteins in neural function, especially at synapses, how their propagation occurs and how pathogenesis is promoted by aging.
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Veeraraghavalu K, Choi SH, Zhang X, Sisodia SS. Endogenous expression of FAD-linked PS1 impairs proliferation, neuronal differentiation and survival of adult hippocampal progenitors. Mol Neurodegener 2013; 8:41. [PMID: 24138759 PMCID: PMC3853710 DOI: 10.1186/1750-1326-8-41] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 10/16/2013] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Alzheimer's disease (AD) is characterized by progressive memory loss and impaired cognitive function. Early-onset familial forms of the disease (FAD) are caused by inheritance of mutant genes encoding presenilin 1 (PS1) variants. We have demonstrated that prion promoter (PrP)-driven expression of human FAD-linked PS1 variants in mice leads to impairments in environmental enrichment (EE)-induced adult hippocampal neural progenitor cell (AHNPC) proliferation and neuronal differentiation, and have provided evidence that accessory cells in the hippocampal niche expressing PS1 variants may modulate AHNPC phenotypes, in vivo. While of significant interest, these latter studies relied on transgenic mice that express human PS1 variant transgenes ubiquitously and at high levels, and the consequences of wild type or mutant PS1 expressed under physiologically relevant levels on EE-mediated AHNPC phenotypes has not yet been tested. RESULTS To assess the impact of mutant PS1 on EE-induced AHNPC phenotypes when expressed under physiological levels, we exposed adult mice that constitutively express the PSEN1 M146V mutation driven by the endogenous PSEN1 promoter (PS1 M146V "knock-in" (KI) mice) to standard or EE-housed conditions. We show that in comparison to wild type PS1 mice, AHNPCs in mice carrying homozygous (PS1M146V/M146V) or heterozygous (PS1M146V/+) M146V mutant alleles fail to exhibit EE-induced proliferation and commitment towards neurogenic lineages. More importantly, we report that the survival of newborn progenitors are diminished in PS1 M146V KI mice exposed to EE-conditions compared to respective EE wild type controls. CONCLUSIONS Our findings reveal that expression at physiological levels achieved by a single PS1 M146V allele is sufficient to impair EE-induced AHNPC proliferation, survival and neuronal differentiation, in vivo. These results and our finding that microglia expressing a single PS1 M146V allele impairs the proliferation of wild type AHNPCs in vitro argue that expression of mutant PS1 in the AHNPC niche impairs AHNPCs phenotypes in a dominant, non-cell autonomous manner.
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Affiliation(s)
| | | | | | - Sangram S Sisodia
- Department of Neurobiology, The University of Chicago, 947 E 58th Street, AB 308, Chicago, Illinois 60637, USA.
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Mutant presenilin 1 expression in excitatory neurons impairs enrichment-mediated phenotypes of adult hippocampal progenitor cells. Proc Natl Acad Sci U S A 2013; 110:9148-53. [PMID: 23674689 DOI: 10.1073/pnas.1302106110] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Inheritance of mutant presenilin 1 genes (PSEN1) encoding presenilin 1 (PS1)variants causes autosomal dominant forms of familial Alzheimer's disease (FAD). We previously reported that ubiquitous expression of FAD-linked PS1 variants in mice impairs environmental enrichment (EE)-induced proliferation and neuronal commitment of adult hippocampal neural progenitor cells (AHNPCs). Notably, the self-renewal and differentiation properties of cultured AHNPCs expressing either human PS1 wild-type or PS1 variants were identical, suggesting that accessory cells within the hippocampal niche expressing PS1 variants may modulate AHNPC phenotypes in vivo. We now report that nontransgenic mouse AHNPCs transduced with retroviruses harboring cDNAs that encode either human PS1 wild-type or FAD-linked PS1 variants show no differences in EE-mediated proliferation and neuronal differentiation. Moreover, conditional inactivation of a mutant PS1 transgene in type-1 primary progenitor cells failed to rescue impairments of EE-induced proliferation, survival, or neurogenesis. In contrast, conditional inactivation of the mutant PS1 transgene in excitatory neurons of the mouse forebrain largely rescued the deficits in EE-induced proliferation and survival of AHNPCs, but not their differentiation into mature neuronal phenotypes. These results persuasively argue for a noncell autonomous effect of FAD-linked PS1 mutants on EE-mediated adult hippocampal neurogenesis.
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Obulesu M, Somashekhar R, Venu R. Genetics of Alzheimer's Disease: An Insight Into Presenilins and Apolipoprotein E Instigated Neurodegeneration. Int J Neurosci 2011; 121:229-36. [DOI: 10.3109/00207454.2010.551432] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Gouras GK, Tampellini D, Takahashi RH, Capetillo-Zarate E. Intraneuronal beta-amyloid accumulation and synapse pathology in Alzheimer's disease. Acta Neuropathol 2010; 119:523-41. [PMID: 20354705 PMCID: PMC3183823 DOI: 10.1007/s00401-010-0679-9] [Citation(s) in RCA: 240] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 03/23/2010] [Accepted: 03/23/2010] [Indexed: 01/01/2023]
Abstract
The aberrant accumulation of aggregated beta-amyloid peptides (Abeta) as plaques is a hallmark of Alzheimer's disease (AD) neuropathology and reduction of Abeta has become a leading direction of emerging experimental therapies for the disease. The mechanism(s) whereby Abeta is involved in the pathophysiology of the disease remain(s) poorly understood. Initially fibrils, and subsequently oligomers of extracellular Abeta have been viewed as the most important pathogenic form of Abeta in AD. More recently, the intraneuronal accumulation of Abeta has been described in the brain, although technical considerations and its relevance in AD have made this a controversial topic. Here, we review the emerging evidence linking intraneuronal Abeta accumulation to the development of synaptic pathology and plaques in AD, and discuss the implications of intraneuronal beta-amyloid for AD pathology, biology, diagnosis and therapy.
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Affiliation(s)
- Gunnar K Gouras
- Department for Neurology and Neuroscience, Weill Cornell Medical College, New York, NY 10065, USA.
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Control of intracellular calcium signaling as a neuroprotective strategy. Molecules 2010; 15:1168-95. [PMID: 20335972 PMCID: PMC2847496 DOI: 10.3390/molecules15031168] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Revised: 02/05/2010] [Accepted: 03/02/2010] [Indexed: 12/13/2022] Open
Abstract
Both acute and chronic degenerative diseases of the nervous system reduce the viability and function of neurons through changes in intracellular calcium signaling. In particular, pathological increases in the intracellular calcium concentration promote such pathogenesis. Disease involvement of numerous regulators of intracellular calcium signaling located on the plasma membrane and intracellular organelles has been documented. Diverse groups of chemical compounds targeting ion channels, G-protein coupled receptors, pumps and enzymes have been identified as potential neuroprotectants. The present review summarizes the discovery, mechanisms and biological activity of neuroprotective molecules targeting proteins that control intracellular calcium signaling to preserve or restore structure and function of the nervous system. Disease relevance, clinical applications and new technologies for the identification of such molecules are being discussed.
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Su B, Wang X, Bonda D, Perry G, Smith M, Zhu X. Abnormal mitochondrial dynamics--a novel therapeutic target for Alzheimer's disease? Mol Neurobiol 2010; 41:87-96. [PMID: 20101529 DOI: 10.1007/s12035-009-8095-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 12/17/2009] [Indexed: 12/27/2022]
Abstract
Mitochondria are dynamic organelles that undergo continuous fission and fusion, which could affect all aspects of mitochondrial function. Mitochondrial dysfunction has been well documented in Alzheimer's disease (AD). In the past few years, emerging evidence indicates that an imbalance of mitochondrial dynamics is involved in the pathogenesis of AD. In this review, we discuss in detail the abnormal mitochondrial dynamics in AD and how such abnormal dynamics may impact mitochondrial and neuronal function and contribute to the course of disease. Based on this discussion, we propose that mitochondrial dynamics could be a potential therapeutic target for AD.
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Affiliation(s)
- Bo Su
- Department of Pathology, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
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15
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Dror V, Kalynyak TB, Bychkivska Y, Frey MHZ, Tee M, Jeffrey KD, Nguyen V, Luciani DS, Johnson JD. Glucose and endoplasmic reticulum calcium channels regulate HIF-1beta via presenilin in pancreatic beta-cells. J Biol Chem 2008; 283:9909-16. [PMID: 18174159 DOI: 10.1074/jbc.m710601200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Pancreatic beta-cell death is a critical event in type 1 diabetes, type 2 diabetes, and clinical islet transplantation. We have previously shown that prolonged block of ryanodine receptor (RyR)-gated release from intracellular Ca(2+) stores activates calpain-10-dependent apoptosis in beta-cells. In the present study, we further characterized intracellular Ca(2+) channel expression and function in human islets and the MIN6 beta-cell line. All three RyR isoforms were identified in human islets and MIN6 cells, and these endoplasmic reticulum channels were observed in close proximity to mitochondria. Blocking RyR channels, but not sarco/endoplasmic reticulum ATPase (SERCA) pumps, reduced the ATP/ADP ratio. Blocking Ca(2+) flux through RyR or inositol trisphosphate receptor channels, but not SERCA pumps, increased the expression of hypoxia-inducible factor (HIF-1beta). Moreover, inhibition of RyR or inositol trisphosphate receptor channels, but not SERCA pumps, increased the expression of presenilin-1. Both HIF-1beta and presenilin-1 expression were also induced by low glucose. Overexpression of presenilin-1 increased HIF-1beta, suggesting that HIF is downstream of presenilin. Our results provide the first evidence of a presenilin-HIF signaling network in beta-cells. We demonstrate that this pathway is controlled by Ca(2+) flux through intracellular channels, likely via changes in mitochondrial metabolism and ATP. These findings provide a mechanistic understanding of the signaling pathways activated when intracellular Ca(2+) homeostasis and metabolic activity are suppressed in diabetes and islet transplantation.
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Affiliation(s)
- Vardit Dror
- Laboratory of Molecular Signaling in Diabetes, Diabetes Research Group, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
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Chen J, Zacharek A, Li A, Cui X, Roberts C, Lu M, Chopp M. Atorvastatin promotes presenilin-1 expression and Notch1 activity and increases neural progenitor cell proliferation after stroke. Stroke 2007; 39:220-6. [PMID: 18063826 DOI: 10.1161/strokeaha.107.490946] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND AND PURPOSE Presenilin1 (PS1) regulates Notch1 signaling activity, which liberates Notch intracellular domain (NICD). Notch activation promotes neural progenitor cell (NPC) self-renewal in the developing brain. In this study, we tested whether atorvastatin-induced NPC proliferation after stroke is mediated by PS1 and Notch1 activation. METHODS PS1 and NICD expressions were measured in retired breeder rats subjected to middle cerebral artery occlusion that were left untreated or treated with atorvastatin. To investigate the mechanisms of atorvastatin-induced NPC self-renewal, subventricular zone (SVZ) neurosphere culture and knockdown of Notch1 gene expression by short interfering RNA were used. SVZ neurosphere formation, cell proliferation, real-time polymerase chain reaction, and Western blotting were performed. RESULTS Atorvastatin significantly increased the numbers of newly generated neuroblasts and promoted PS1 and NICD expression in the ipsilateral and homologous contralateral SVZ compared with saline-treated control rats. Increased SVZ neurosphere formation and cell proliferation were found in cultured neurospheres derived from normal rat and poststroke rat SVZs treated in vitro with atorvastatin compared with untreated neurospheres (P<0.05). Atorvastatin significantly increased PS1 and hairy and enhancer of split1 (Hes1) gene expression in cultured SVZ neurospheres. Inhibition of PS1 significantly decreased NICD expression. Short interfering RNA knockdown of Notch1 expression, decreased NPC proliferation, and NICD and hairy and enhancer of split1 expression in cultured neurosphere cells. CONCLUSIONS These data indicate that atorvastatin increases the NPC pool in older rats and that it also upregulates PS1 expression and Notch1 signaling activity, which in turn, facilitate an increase in SVZ NPC proliferation.
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Affiliation(s)
- Jieli Chen
- Department of Neurology, Henry Ford Health Sciences Center, Detroit, MI 48202, USA.
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17
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Li M, Chen L, Lee DHS, Yu LC, Zhang Y. The role of intracellular amyloid beta in Alzheimer's disease. Prog Neurobiol 2007; 83:131-9. [PMID: 17889422 DOI: 10.1016/j.pneurobio.2007.08.002] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 06/16/2007] [Accepted: 08/03/2007] [Indexed: 01/05/2023]
Abstract
Extracellular amyloid beta (Abeta) that confers neurotoxicity and modulates synaptic plasticity and memory function has been central to the amyloid hypothesis of Alzheimer's disease (AD) pathology. Like many other misfolded proteins identified in neurodegenerative disorders, Abeta also accumulates inside the AD neurons. This intracellular Abeta affects a variety of cellular physiology from protein degradation, axonal transport, autophagy to apoptosis, further documenting the role of Abeta in AD. Therapeutics targeting intracellular Abeta could be effective treatment for AD.
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Affiliation(s)
- Meng Li
- Laboratory of Neurobiology and State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing 100871, China
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18
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Kodam A, Vetrivel KS, Thinakaran G, Kar S. Cellular distribution of gamma-secretase subunit nicastrin in the developing and adult rat brains. Neurobiol Aging 2007; 29:724-38. [PMID: 17222950 PMCID: PMC2871253 DOI: 10.1016/j.neurobiolaging.2006.12.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Revised: 12/01/2006] [Accepted: 12/05/2006] [Indexed: 11/20/2022]
Abstract
Nicastrin and presenilin 1 are integral components of the high molecular weight gamma-secretase complexes that regulate proteolytic processing of various type I membrane proteins including amyloid precursor protein and Notch. At present, there is little information regarding the cellular distribution of nicastrin in the developing or adult rat brain. We report here, using immunoblotting and immunohistochemical methods, that nicastrin in the adult rat brain is widely expressed and co-localized with presenilin 1 in select neuronal populations within all major areas, including the basal forebrain, striatum, cortex, hippocampus, amygdala, thalamus, hypothalamus, cerebellum and brainstem. We also observed dense neuropil labeling in many regions in the brain, suggesting that nicastrin gets transported to dendrites and/or axon terminals in the central nervous system. The levels of nicastrin are found to be relatively high at the early stages of postnatal development and then declined gradually to reach the adult profile. At the cellular level, nicastrin is localized predominantly in neuronal cell bodies at early postnatal stages, but is apparent both in cell bodies and dendrites/neuropil in all brain regions at the later stages. The regulation of nicastrin expression and localization during development and its distribution in a wide spectrum of neurons in the postnatal and adult rat brains provide an anatomical basis to suggest a multifunctional role for the gamma-secretase complex in the developing and adult rat brains.
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Affiliation(s)
- A Kodam
- Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
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19
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Small SA, Gandy S. Sorting through the cell biology of Alzheimer's disease: intracellular pathways to pathogenesis. Neuron 2006; 52:15-31. [PMID: 17015224 PMCID: PMC4820242 DOI: 10.1016/j.neuron.2006.09.001] [Citation(s) in RCA: 253] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
During the first 100 years of Alzheimer's disease research, this devastating and intractable disorder has been characterized at the clinical, histological, and molecular levels. Nevertheless, many key mechanistic questions remain unanswered. Here we will emphasize the importance of the cell biology of Alzheimer's disease, reviewing the relevant literature that has expanded our mechanistic understanding, with a particular focus on pathways regulating protein sorting. Accumulated evidence indicates that sorting pathways may be uniquely vulnerable to disease pathogenesis, and recent studies have begun to reveal disease-related defects in the regulation of protein sorting.
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Affiliation(s)
- Scott A. Small
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Department of Neurology, Columbia University College of Physicians and Surgeons, New York, New York 10032
- Correspondence: (S.A.S.), (S.G.)
| | - Sam Gandy
- Farber Institute for Neurosciences of Thomas Jefferson University, Philadelphia, Pennsylvania 19107
- Correspondence: (S.A.S.), (S.G.)
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20
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Abstract
Development and implementation of microarray techniques to quantify expression levels of dozens to hundreds to thousands of transcripts simultaneously within select tissue samples from normal control subjects and neurodegenerative diseased brains has enabled scientists to create molecular fingerprints of vulnerable neuronal populations in Alzheimer's disease (AD) and related disorders. A goal is to sample gene expression from homogeneous cell types within a defined region without potential contamination by expression profiles of adjacent neuronal subpopulations and nonneuronal cells. The precise resolution afforded by single cell and population cell RNA analysis in combination with microarrays and real-time quantitative polymerase chain reaction (qPCR)-based analyses allows for relative gene expression level comparisons across cell types under different experimental conditions and disease progression. The ability to analyze single cells is an important distinction from global and regional assessments of mRNA expression and can be applied to optimally prepared tissues from animal models of neurodegeneration as well as postmortem human brain tissues. Gene expression analysis in postmortem AD brain regions including the hippocampal formation and neocortex reveals selectively vulnerable cell types share putative pathogenetic alterations in common classes of transcripts, for example, markers of glutamatergic neurotransmission, synaptic-related markers, protein phosphatases and kinases, and neurotrophins/neurotrophin receptors. Expression profiles of vulnerable regions and neurons may reveal important clues toward the understanding of the molecular pathogenesis of various neurological diseases and aid in identifying rational targets toward pharmacotherapeutic interventions for progressive, late-onset neurodegenerative disorders such as mild cognitive impairment (MCI) and AD.
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Affiliation(s)
- Stephen D Ginsberg
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY 10962, USA.
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21
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Zhang M, Haapasalo A, Kim DY, Ingano LAM, Pettingell WH, Kovacs DM. Presenilin/γ‐secretase activity regulates protein clearance from the endocytic recycling compartment. FASEB J 2006; 20:1176-8. [PMID: 16645046 DOI: 10.1096/fj.05-5531fje] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The presenilin (PS)/gamma-secretase complex proteolytically cleaves more than 20 different proteins in addition to the amyloid precursor protein (APP). These substrates are almost exclusively type I membrane proteins. Many undergo internalization from the cell surface followed by degradation or recycling back to the plasma membrane through the endocytic recycling compartment (ERC). Evidence shows that the PSs also regulate intracellular trafficking of APP and its C-terminal fragments (CTFs). To investigate whether PS/gamma-secretase activity is required for normal endosomal recycling, we performed live cell imaging experiments with fluorescently labeled transferrin, reported to specifically traffic through the ERC. By using pharmacological gamma-secretase inhibitors or cell lines lacking functional PS/gamma-secretase, here we show that PS/gamma-secretase activity is required for clearance of transferrin from the ERC. Interestingly, lack of PS/gamma-secretase function also resulted in the accumulation of APP and APP-CTFs in the ERC in addition to the cell surface. Familial Alzheimer's disease mutations in APP-CTFs did not affect endocytic recycling of these proteins. Our results suggest that PS/gamma-secretase activity is required for normal endosomal recycling of soluble and membrane-associated proteins through the ERC and propose a new mechanism by which impaired PS/gamma-secretase function may eventually contribute to neurodegeneration.
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Affiliation(s)
- Mei Zhang
- Neurobiology of Disease Laboratory, Genetics and Aging Research Unit, Department of Neurology/MIND, Massachusetts General Hospital, Harvard Medical School, 114 16th Street, Charlestown, Massachusetts 02129, USA
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22
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Uchihara T, Sanjo N, Nakamura A, Han K, Song SY, St George-Hyslop P, Fraser PE. Transient abundance of presenilin 1 fragments/nicastrin complex associated with synaptogenesis during development in rat cerebellum. Neurobiol Aging 2006; 27:88-97. [PMID: 16298244 DOI: 10.1016/j.neurobiolaging.2004.12.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2004] [Revised: 11/09/2004] [Accepted: 12/20/2004] [Indexed: 10/25/2022]
Abstract
Immunolocalization and expression of endogenous nicastrin (NCT) and presenilin 1 (PS1) fragments during postnatal development of rat cerebellum were investigated with fragment-specific antibodies. Immunoblotting for NCT revealed the expected mature and immature species, which gradually declined during development. In contrast, the expression of PS1 N-terminal fragment exhibited a peak at postnatal day 14 (P14) and declined thereafter. This chronological change was similarly observed with PS1 C-terminal fragment. Immunoprecipitation of NCT indicated its physical association with PS1 fragments. Colocalization of these molecules to the endoplasmic reticulum in cerebellar Purkinje cells indicates that they are organized into a complex in developing neurons. In addition, active sites of synaptogenesis, the base of the external granular layer and glomeruli, contained PS1 fragments and smaller amount of NCT. Isolated synaptic fraction contained both PS1 and NCT, suggesting their functional association within synapses. Transient abundance of NCT and PS1 fragments as a complex, when (P14) and where synaptogenesis is active, is consistent with intracellular trafficking of this complex in developing neurons and suggests its role as gamma-secretase in synaptogenesis.
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Affiliation(s)
- Toshiki Uchihara
- Department of Neuropathology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashi-dai, Fuchu, Tokyo, 183-8526 Japan.
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23
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Abstract
Mutations in presenilins are the major cause of familial Alzheimer disease. The involvement of presenilins in the pathogenesis of Alzheimer disease, therefore, has been the subject of intense investigation during the past decade. Genetic analysis of phenotypes associated with presenilin mutations in invertebrate and vertebrate systems has greatly advanced our understanding of the in vivo functions of presenilins. In this review, the authors will summarize the current understanding of presenilin function, with an emphasis on the mammalian cerebral cortex. During development, presenilins play crucial roles in the maintenance of neural progenitor cell proliferation, the temporal control of neuronal differentiation, the survival of Cajal-Retzius neurons, and proper neuronal migration in the developing cerebral cortex. Analysis of presenilin function in the adult cerebral cortex has revealed essential roles for presenilins in synaptic plasticity, long-term memory, and neuronal survival. The authors will also discuss the molecular mechanisms through which presenilins may mediate these functions, including the Notch, CREB, and NMDA receptor-mediated signaling pathways. These diverse functions of presenilins in cortical development and function and neuronal survival have important implications for the pathogenesis of neurodegenerative dementia.
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Affiliation(s)
- Mary Wines-Samuelson
- Center for Neurologic Diseases, Brigham and Women's Hospital, Program in Neuroscience, Harvard Medical School, Boston, Massachussetts 02115, USA
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24
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Chevallier NL, Soriano S, Kang DE, Masliah E, Hu G, Koo EH. Perturbed neurogenesis in the adult hippocampus associated with presenilin-1 A246E mutation. THE AMERICAN JOURNAL OF PATHOLOGY 2005; 167:151-9. [PMID: 15972961 PMCID: PMC1603433 DOI: 10.1016/s0002-9440(10)62962-8] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In addition to its well-established role in gamma-secretase cleavage, presenilin (PS) also plays a role in regulating the stability of cytosolic beta-catenin, a protein involved in Wnt signaling. Several familial Alzheimer's disease-associated PS1 mutations have been shown to increase the stability of the signaling pool of beta-catenin, correlating with enhanced cell proliferation. Accordingly, we hypothesized that in the setting of PS1 mutations, abnormal activation of Wnt/beta-catenin signaling leads to increased cell division. We tested this hypothesis by examining whether there is evidence of increased neurogenesis in the hippocampus of adult transgenic mice that overexpress the PS1 A246E mutation. In PS1/PS2-deficient fibroblasts, expression of PS1 A246E Familial AD mutation failed to restore the rapid turnover of beta-catenin compared with wild-type PS1. We then examined whether the same mutation enhanced neurogenesis in vivo in adult hippocampus of PS1-deficient mice when restored by wild-type human PS1 (PS1(-/-)WT) or A246E PS1 mutation (PS1(-/-)AE). The PS1 A246E mutation stimulated the proliferation of progenitor cells in the dentate gyrus of adult mice, as assessed by 5-bromo-2-deoxyuridine incorporation, but did not influence their survival or differentiation. These observations suggest that the PS1 A246E mutation influences cell growth putatively via abnormal beta-catenin signaling in vivo.
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Affiliation(s)
- Nathalie L Chevallier
- Department of Neurosciences, University of California-San Diego, School of Medicine, La Jolla, California 92093-0691, USA
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25
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Abstract
Alzheimer's disease (AD) is the most common form of dementia and is characterized pathologically by the accumulation of beta-amyloid (Abeta) plaques and neurofibrillary tangles in the brain. Genetic studies of AD first highlighted the importance of the presenilins (PS). Subsequent functional studies have demonstrated that PS form the catalytic subunit of the gamma-secretase complex that produces the Abeta peptide, confirming the central role of PS in AD biology. Here, we review the studies that have characterized PS function in the gamma-secretase complex in Caenorhabditis elegans, mice and in in vitro cell culture systems, including studies of PS structure, PS interactions with substrates and other gamma-secretase complex members, and the evidence supporting the hypothesis that PS are aspartyl proteases that are active in intramembranous proteolysis. A thorough knowledge of the mechanism of PS cleavage in the context of the gamma-secretase complex will further our understanding of the molecular mechanisms that cause AD, and may allow the development of therapeutics that can alter Abeta production and modify the risk for AD.
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Affiliation(s)
- A L Brunkan
- Department of Psychiatry, Washington University School of Medicine, St Louis, MO 63100, USA
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26
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Chong ZZ, Li F, Maiese K. Oxidative stress in the brain: novel cellular targets that govern survival during neurodegenerative disease. Prog Neurobiol 2005; 75:207-46. [PMID: 15882775 DOI: 10.1016/j.pneurobio.2005.02.004] [Citation(s) in RCA: 409] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2004] [Revised: 02/16/2005] [Accepted: 02/16/2005] [Indexed: 01/28/2023]
Abstract
Despite our present knowledge of some of the cellular pathways that modulate central nervous system injury, complete therapeutic prevention or reversal of acute or chronic neuronal injury has not been achieved. The cellular mechanisms that precipitate these diseases are more involved than initially believed. As a result, identification of novel therapeutic targets for the treatment of cellular injury would be extremely beneficial to reduce or eliminate disability from nervous system disorders. Current studies have begun to focus on pathways of oxidative stress that involve a variety of cellular pathways. Here we discuss novel pathways that involve the generation of reactive oxygen species and oxidative stress, apoptotic injury that leads to nuclear degradation in both neuronal and vascular populations, and the early loss of cellular membrane asymmetry that mitigates inflammation and vascular occlusion. Current work has identified exciting pathways, such as the Wnt pathway and the serine-threonine kinase Akt, as central modulators that oversee cellular apoptosis and their downstream substrates that include Forkhead transcription factors, glycogen synthase kinase-3beta, mitochondrial dysfunction, Bad, and Bcl-x(L). Other closely integrated pathways control microglial activation, release of inflammatory cytokines, and caspase and calpain activation. New therapeutic avenues that are just open to exploration, such as with brain temperature regulation, nicotinamide adenine dinucleotide modulation, metabotropic glutamate system modulation, and erythropoietin targeted expression, may provide both attractive and viable alternatives to treat a variety of disorders that include stroke, Alzheimer's disease, and traumatic brain injury.
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Affiliation(s)
- Zhao Zhong Chong
- Division of Cellular and Molecular Cerebral Ischemia, Wayne State University School of Medicine, Detroit, MI 48201, USA
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27
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Siman R, Salidas S. Gamma-secretase subunit composition and distribution in the presenilin wild-type and mutant mouse brain. Neuroscience 2005; 129:615-28. [PMID: 15541883 DOI: 10.1016/j.neuroscience.2004.08.028] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2004] [Indexed: 10/26/2022]
Abstract
Studies conducted in cell culture indicate that the gamma-secretase involved in amyloid beta-formation and Notch signaling is a multisubunit aspartic protease. Little is known, however, of the structure, function, or localization of gamma-secretase in the adult brain, or possible effects of familial Alzheimer's disease (FAD)-causing mutations on the brain protease. We report here that mouse brain contains a complex composed of gamma-secretase subunits presenilin-1 N-terminal fragment, presenilin-1 C-terminal fragment, Nicastrin, Aph-1a and Pen-2. A homozygous FAD-linked Presenilin-1 knock-in mutation does not alter relative subunit levels. Immunocytochemical localization of gamma-secretase subunits revealed overlapping but distinct regional and subcellular distributions. All subunits are expressed throughout the neuraxis predominantly in neurons, and are present in axons. Their distributions and levels of expression are unaffected by mutant presenilin-1. In a presenilin-1/amyloid precursor protein double knock-in mouse, subunits are associated with plaques, but are expressed at similar levels in amyloid-rich and -poor regions. gamma-Secretase subunits are distributed much more extensively than circumscribed amyloid deposits, suggesting the importance of other factors for localized amyloid deposition. These results indicate a widespread neuronal function for gamma-secretase in the adult brain, and suggest the pathogenic mechanism of FAD-linked mutations does not involve alterations in the composition, expression or brain distribution of the protease. The subcellular localization of gamma-secretase subunits is consistent with a nerve terminal source for amyloid aggregates.
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Affiliation(s)
- R Siman
- Department of Pharmacology, University of Pennsylvania School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104-6084, USA.
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28
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Cupers P, Annaert WG, Strooper BD. The presenilins as potential drug targets in Alzheimer’s disease. ACTA ACUST UNITED AC 2005. [DOI: 10.1517/14728222.3.3.413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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29
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Chong ZZ, Li F, Maiese K. Stress in the brain: novel cellular mechanisms of injury linked to Alzheimer's disease. ACTA ACUST UNITED AC 2005; 49:1-21. [PMID: 15960984 PMCID: PMC2276700 DOI: 10.1016/j.brainresrev.2004.11.005] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Revised: 09/28/2004] [Accepted: 11/12/2004] [Indexed: 01/24/2023]
Abstract
More than a century has elapsed since the description of Alois Alzheimer's patient Auguste D. Yet, the well-documented generation of beta-amyloid aggregates and neurofibrillary tangles that define Alzheimer's disease is believed to represent only a portion of the cellular processes that can determine the course of Alzheimer's disease. Understanding of the complex nature of this disorder has evolved with an increased appreciation for pathways that involve the generation of reactive oxygen species and oxidative stress, apoptotic injury that leads to nuclear degradation in both neuronal and vascular populations, and the early loss of cellular membrane asymmetry that mitigates inflammation and vascular occlusion. Recent work has identified novel pathways, such as the Wnt pathway and the serine-threonine kinase Akt, as central modulators that oversee cellular apoptosis and the formation of neurofibrillary tangles through their downstream substrates that include glycogen synthase kinase-3beta, Bad, and Bcl-xL. Other closely integrated pathways control microglial activation, release of inflammatory cytokines, and caspase and calpain activation for the processing of amyloid precursor protein, tau protein cleavage, and presenilin disposal. New therapeutic avenues that are just open to exploration, such as with nicotinamide adenine dinucleotide modulation, cell cycle modulation, metabotropic glutamate system modulation, and erythropoietin targeted expression, may provide both attractive and viable alternatives to treat Alzheimer's disease.
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Affiliation(s)
- Zhao Zhong Chong
- Division of Cellular and Molecular Cerebral Ischemia, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Faqi Li
- Division of Cellular and Molecular Cerebral Ischemia, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Kenneth Maiese
- Division of Cellular and Molecular Cerebral Ischemia, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Departments of Neurology and Anatomy and Cell Biology, Center for Molecular Medicine and Genetics, Institute of Environmental Health Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Corresponding author. Department of Neurology, 8C-1 UHC, Wayne State University School of Medicine, 4201 St. Antoine, Detroit, MI 48201. Fax: +1 313 966 0486. E-mail address: (K. Maiese)
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30
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Suga K, Tomiyama T, Mori H, Akagawa K. Syntaxin 5 interacts with presenilin holoproteins, but not with their N- or C-terminal fragments, and affects beta-amyloid peptide production. Biochem J 2004; 381:619-28. [PMID: 15109302 PMCID: PMC1133870 DOI: 10.1042/bj20040618] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2004] [Accepted: 04/27/2004] [Indexed: 12/16/2022]
Abstract
Mutations in presenilins 1 and 2 (PS1 and PS2) account for the majority of cases of early-onset familial Alzheimer's disease. However, the trafficking and interaction of PSs with other proteins in the early secretory pathways are poorly understood. Using co-immunoprecipitation, we found that PS bound to Syx5 (syntaxin 5), which is a target-soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor involved in endoplasmic reticulum (ER)-Golgi vesicular transport in vivo. Syx5 interacted only with the full-length PS holoproteins and not with the naturally occurring N- or C-terminal fragments. The PS holoproteins co-immunoprecipitated with the mutant Syx5, which localized to the ER and Golgi compartments, despite the substitution of the transmembrane region with that of syntaxin 1A. In contrast, the transmembrane deletion mutant that localized to the cytosol, but not to the ER or Golgi compartments, did not co-immunoprecipitate the PS holoproteins. The PS1 variant linked to familial Alzheimer's disease (PS1DeltaE9), lacking the region that contains the endoproteolytic cleavage site in the cytoplasmic loop, showed markedly decreased binding to Syx5. Immunofluorescence and sucrose-density-gradient fractionation analyses showed that the full-length PS holoproteins co-localized with Syx5 to the ER and cis-Golgi compartments. Furthermore, Syx5 overexpression resulted in the accumulation of PS holoproteins and the beta-amyloid precursor protein, and reduced the secretion of the Abeta (amyloid beta) peptide in COS-7 cells. In summary, these results indicate that Syx5 binds to full-length PSs and affects the processing and trafficking of beta-amyloid precursor protein in the early secretory compartments.
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Affiliation(s)
- Kei Suga
- Department of Cell Physiology, Kyorin University School of Medicine, 6-20-2, Shinkawa, Mitaka, Tokyo 181-8611, Japan.
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31
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Ilaya NT, Evin G, Masters CL, Culvenor JG. Nicastrin expression in mouse peripheral tissues is not co-ordinated with presenilin and is high in muscle. J Neurochem 2004; 91:230-7. [PMID: 15379903 DOI: 10.1111/j.1471-4159.2004.02718.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nicastrin was the first binding partner of presenilin (PS) shown to be a critical component of the presenilin/gamma-secretase complex essential in development and differentiation, and in generation of Alzheimer's disease Abeta amyloid peptide. To investigate the function of this glycoprotein, we compared nicastrin and presenilin protein expression in various mouse tissues. Western blot analysis of PS1, PS2 and nicastrin indicates their expression levels are not coordinated. In adult mouse, nicastrin is highly expressed in muscle membranes, whereas presenilin levels are very low. By Blue Native electrophoresis, a PS1 complex of 400 kDa was detected in lung, brain, thymus and heart; nicastrin was also detected as a 400-kDa complex in brain but in muscle it was detected with a complex mobility of 240 and 290 kDa, suggesting association with alternate protein complexes. Immunocytochemistry confirms strong intracellular expression of nicastrin in skeletal muscle and blood vessel smooth muscle. These findings suggest a function for nicastrin in muscle other than participation in the gamma-secretase complex.
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Affiliation(s)
- Nancy T Ilaya
- Department of Pathology, The University of Melbourne, Parkville, Victoria, Australia
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32
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Vetrivel KS, Cheng H, Lin W, Sakurai T, Li T, Nukina N, Wong PC, Xu H, Thinakaran G. Association of gamma-secretase with lipid rafts in post-Golgi and endosome membranes. J Biol Chem 2004; 279:44945-54. [PMID: 15322084 PMCID: PMC1201506 DOI: 10.1074/jbc.m407986200] [Citation(s) in RCA: 333] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alzheimer's disease-associated beta-amyloid peptides (Abeta) are generated by the sequential proteolytic processing of amyloid precursor protein (APP) by beta- and gamma-secretases. There is growing evidence that cholesterol- and sphingolipid-rich membrane microdomains are involved in regulating trafficking and processing of APP. BACE1, the major beta-secretase in neurons is a palmitoylated transmembrane protein that resides in lipid rafts. A subset of APP is subject to amyloidogenic processing by BACE1 in lipid rafts, and this process depends on the integrity of lipid rafts. Here we describe the association of all four components of the gamma-secretase complex, namely presenilin 1 (PS1)-derived fragments, mature nicastrin, APH-1, and PEN-2, with cholesterol-rich detergent insoluble membrane (DIM) domains of non-neuronal cells and neurons that fulfill the criteria of lipid rafts. In PS1(-/-)/PS2(-/-) and NCT(-/-) fibroblasts, gamma-secretase components that still remain fail to become detergent-resistant, suggesting that raft association requires gamma-secretase complex assembly. Biochemical evidence shows that subunits of the gamma-secretase complex and three TGN/endosome-resident SNAREs cofractionate in sucrose density gradients, and show similar solubility or insolubility characteristics in distinct non-ionic and zwitterionic detergents, indicative of their co-residence in membrane microdomains with similar protein-lipid composition. This notion is confirmed using magnetic immunoisolation of PS1- or syntaxin 6-positive membrane patches from a mixture of membranes with similar buoyant densities following Lubrol WX extraction or sonication, and gradient centrifugation. These findings are consistent with the localization of gamma-secretase in lipid raft microdomains of post-Golgi and endosomes, organelles previously implicated in amyloidogenic processing of APP.
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Affiliation(s)
| | - Haipeng Cheng
- From the Department of Neurobiology, Pharmacology and Physiology and the
| | - William Lin
- Committee on Neurobiology, The University of Chicago, Chicago, Illinois 60637, the
| | - Takashi Sakurai
- Laboratory for Neurodegeneration Signal and Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Saitama, 351-0198, Japan, the
| | - Tong Li
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, and the
| | - Nobuyuki Nukina
- Laboratory for Neurodegeneration Signal and Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Saitama, 351-0198, Japan, the
| | - Philip C. Wong
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, and the
| | - Huaxi Xu
- Center for Neuroscience and Aging, The Burnham Institute, La Jolla, California 92037
| | - Gopal Thinakaran
- From the Department of Neurobiology, Pharmacology and Physiology and the
- Committee on Neurobiology, The University of Chicago, Chicago, Illinois 60637, the
- §§ To whom correspondence should be addressed. Tel.: 773-834-3752; Fax: 773-834-3808; E-mail:
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Khvotchev M, Südhof TC. Proteolytic processing of amyloid-beta precursor protein by secretases does not require cell surface transport. J Biol Chem 2004; 279:47101-8. [PMID: 15316009 DOI: 10.1074/jbc.m408474200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cleavage of amyloid-beta precursor protein (APP) by alpha-,beta-, and gamma-secretases releases an extracellular fragment called APPS, small Abeta peptides, and a short APP intracellular domain that may provide a transcriptional signal analogous to the Notch intracellular domain. Notch cleavage is activated by extracellular ligands on the cell surface, but the cellular localization of APP cleavage remains unclear. We now show that in transfected cultured cells, the plasma membrane SNARE protein syntaxin 1A, when expressed as a full-length protein, disrupts the Golgi apparatus and blocks trans-Golgi traffic and exocytosis. In contrast, truncated syntaxin 1A1-243 selectively abolishes exocytosis but has no apparent effect on trans-Golgi traffic or Golgi structure, whereas further truncated syntaxins 1A1-236 and 1A1-230 have no effect on either exocytosis or Golgi traffic. Using these syntaxin 1A fragments, we demonstrated that blocking trans-Golgi traffic greatly impairs APP cleavage and AICD-dependent nuclear signaling, whereas blocking exocytosis alone does not affect either process, even though secretion of APPS and Abeta40 peptide is abolished. Our data suggest that, different from Notch, cleavage of APP is independent of cell surface regulation by extracellular ligands but may be controlled by intracellular signaling.
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Affiliation(s)
- Mikhail Khvotchev
- Center for Basic Neuroscience, Department of Molecular Genetics, and Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-9111, USA
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34
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Zou Z, Chung B, Nguyen T, Mentone S, Thomson B, Biemesderfer D. Linking Receptor-mediated Endocytosis and Cell Signaling. J Biol Chem 2004; 279:34302-10. [PMID: 15180987 DOI: 10.1074/jbc.m405608200] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Megalin, a member of the low density lipoprotein receptor gene family, is required for efficient protein absorption in the proximal tubule. Recent studies have shown that the low density lipoprotein receptor-related protein, another member of this gene family, is proteolytically processed by gamma-secretase implying a role for low density lipoprotein receptor-related protein in a Notchlike signaling pathway. This pathway has been shown to involve: 1) metalloprotease-mediated ectodomain shedding and gamma-secretase-mediated intramembrane proteolysis of some receptors. Experiments were performed to determine whether megalin undergoes similar processing. By immunocytochemistry, immunoblotting, and a fluorogenic enzyme assay presenilin-1 (required for gamma-secretase activity) and gamma-secretase activity were found in the brush border of proximal kidney tubules where megalin is localized. Using a fluorogenic peptide containing an amyloid precursor protein gamma-secretase cleavage site and Compound E, a specific gamma-secretase inhibitor, we found high levels of gamma-secretase activity in renal brush border membrane vesicles. Immunoblotting analysis of renal microsomes and opossum kidney proximal tubule (OKP) cells using antibodies directed to the cytosolic domain of megalin showed a 35-40-kDa, membrane-associated, carboxyl-terminal fragment of megalin (MCTF). When cells were incubated with 200 nm phorbol 12-myristate 13-acetate, the appearance of the MCTF increased 2.5-fold and was blocked by metalloprotease inhibitors. When the cells were incubated with gamma-secretase inhibitor Compound E, it caused a 2-fold increase in MCTF. Finally, incubating the cells with 1 microm vitamin D-binding protein resulted in a 25% increase in the appearance of the MCTF. In summary, the MCTF is produced by protein kinase C regulated, metalloprotease-mediated ectodomain shedding and is the substrate for gamma-secretase. We postulate that the enzymatic processing of megalin represents part of a novel ligand-dependent signaling pathway in the proximal tubule that links receptor-mediated endocytosis with cell signaling.
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Affiliation(s)
- Zhiying Zou
- Department of Internal Medicine, School of Medicine, Yale University, New Haven, CT 06520-8029, USA
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35
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Ribaut-Barassin C, Dupont JL, Haeberlé AM, Bombarde G, Huber G, Moussaoui S, Mariani J, Bailly Y. Alzheimer's disease proteins in cerebellar and hippocampal synapses during postnatal development and aging of the rat. Neuroscience 2003; 120:405-23. [PMID: 12890511 DOI: 10.1016/s0306-4522(03)00332-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Alzheimer's dementia may be considered a synaptic disease of central neurons: the loss of synapses, reflected by early cognitive impairments, precedes the appearance of extra cellular focal deposits of beta-amyloid peptide in the brain of patients. Distinct immunocytochemical patterns of amyloid precursor proteins (APPs) have previously been demonstrated in the synapses by ultrastructural analysis in the cerebellum and hippocampus of adult rats and mice. Now we show that during postnatal development and during aging in these structures, the immunocytochemical expression of APPs increases in the synapses in parallel with the known up-regulation of total APPs brain levels. Interestingly, as shown previously in the adult rodents, the presenilins (PSs) 1 and 2, which intervene in APPs metabolism, exhibit a synaptic distribution pattern similar to that of APPs with parallel quantitative changes throughout life. In the brain tissue, single and double immunocytochemistry at the ultrastructural level shows co-localisation of APPs and PSs in axonal and dendritic synaptic compartments during postnatal synaptogenesis, adulthood and aging. In addition, double-labelling immunocytofluorescence detects these proteins close to synaptophysin at the growth cones of developing cultured neurons. Thusly, the brain expression of APPs and PSs appears to be regulated synchronously during lifespan in the synaptic compartments where the proteins are colocated. This suggests that PS-dependent processing of important synaptic proteins such as APPs could intervene in age-induced adjustments of synaptic relationships between specific types of neurons.
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Affiliation(s)
- C Ribaut-Barassin
- Neurotransmission et Sécrétion Neuroendocrine, UPR 2356 CNRS et IFR 37 des Neurosciences, 5 rue Blaise Pascal, 67084 Strasbourg, France
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36
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Abstract
Presenilins (PS) constitute a fascinating family of proteins that play crucial roles in several major signalling processes involved in key cellular functions and are also closely associated with dysfunction in Alzheimer's disease (AD). Presenilin-dependent intramembrane cleavage of transmembrane proteins such as amyloid beta precursor protein (AbetaPP) and Notch resides in a high-molecular-weight gamma-secretase protein complex, of which at least five core components have now been identified. Remarkably, it has now become evident that presenilin-dependent gamma-secretase activity extends beyond its role in AbetaPP and Notch cleavages to have a generic role in the regulated intramembranous cleavage of certain membrane proteins. Actually, a new picture is emerging in which cells can relay signals from the extracellular space to their interior through presenilin-dependent proteolysis within the membrane-spanning regions of type 1 integral membrane proteins to generate potential transcriptionally active intracellular fragments. This review deals with the complex biology of presenilins and focuses more specifically on recent developments regarding the composition, assembly and regulation of the gamma-secretase protein complex, its substrates and its implications for cellular signalling.
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Affiliation(s)
- Miguel Medina
- Cavalieri Ottolenghi Scientific Institute, Universita degli Studi di Torino, AO San Luigi Gonzaga, Regione Gonzole 10, Orbassano, Turin 10043, Italy.
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37
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Grbovic OM, Mathews PM, Jiang Y, Schmidt SD, Dinakar R, Summers-Terio NB, Ceresa BP, Nixon RA, Cataldo AM. Rab5-stimulated up-regulation of the endocytic pathway increases intracellular beta-cleaved amyloid precursor protein carboxyl-terminal fragment levels and Abeta production. J Biol Chem 2003; 278:31261-8. [PMID: 12761223 DOI: 10.1074/jbc.m304122200] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously identified abnormalities of the endocytic pathway in neurons as the earliest known pathology in sporadic Alzheimer's disease (AD) and Down's syndrome brain. In this study, we modeled aspects of these AD-related endocytic changes in murine L cells by overexpressing Rab5, a positive regulator of endocytosis. Rab5-transfected cells exhibited abnormally large endosomes immunoreactive for Rab5 and early endosomal antigen 1, resembling the endosome morphology seen in affected neurons from AD brain. The levels of both Abeta40 and Abeta42 in conditioned medium were increased more than 2.5-fold following Rab5 overexpression. In Rab5 overexpressing cells, the levels of beta-cleaved amyloid precursor protein (APP) carboxyl-terminal fragments (betaCTF), the rate-limiting proteolytic intermediate in Abeta generation, were increased up to 2-fold relative to APP holoprotein levels. An increase in beta-cleaved soluble APP relative to alpha-cleaved soluble APP was also observed following Rab5 overexpression. BetaCTFs were co-localized by immunolabeling to vesicular compartments, including the early endosome and the trans-Golgi network. These results demonstrate a relationship between endosomal pathway activity, betaCTF generation, and Abeta production. Our findings in this model system suggest that the endosomal pathology seen at the earliest stage of sporadic AD may contribute to APP proteolysis along a beta-amyloidogenic pathway.
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Affiliation(s)
- Olivera M Grbovic
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York 10962, USA.
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38
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Réchards M, Xia W, Oorschot VMJ, Selkoe DJ, Klumperman J. Presenilin-1 exists in both pre- and post-Golgi compartments and recycles via COPI-coated membranes. Traffic 2003; 4:553-65. [PMID: 12839498 DOI: 10.1034/j.1600-0854.2003.t01-1-00114.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Presenilin-1 is involved in intramembrane proteolysis of various proteins, but its intracellular site of action has remained elusive. Here, we determined by quantitative immunogold-electron microscopy that presenilin-1 in Chinese hamster ovary cells is present in pre-Golgi compartments as well as at the plasma membrane and endosomes. Notably, a high percentage of presenilin-1 resides in COPI-coated membranes between the endoplasmic reticulum and the Golgi complex, indicating significant recycling to the endoplasmic reticulum. By contrast, the inactive aspartate mutant presenilin-1D257A is relatively excluded from COPI-coated membranes, concomitant with increased post-Golgi levels. These data provide critical evidence for the scenario that the complex containing presenilin-1 can serve as gamma-secretase at the plasma membrane or endosomes and suggest a role for COPI-mediated retrograde transport in regulating post-Golgi levels of presenilin-1.
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Affiliation(s)
- Marloes Réchards
- Department of Cell Biology, University Medical Center and Institute for Biomembranes, Center for Biomedical Genetics, Utrecht University, 3584 CX Utrecht, The Netherlands
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39
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Pasternak SH, Bagshaw RD, Guiral M, Zhang S, Ackerley CA, Pak BJ, Callahan JW, Mahuran DJ. Presenilin-1, nicastrin, amyloid precursor protein, and gamma-secretase activity are co-localized in the lysosomal membrane. J Biol Chem 2003; 278:26687-94. [PMID: 12736250 DOI: 10.1074/jbc.m304009200] [Citation(s) in RCA: 222] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Alzheimer's disease (AD) is caused by the cerebral deposition of beta-amyloid (Abeta), a 38-43-amino acid peptide derived by proteolytic cleavage of the amyloid precursor protein (APP). Initial studies indicated that final cleavage of APP by the gamma-secretase (a complex containing presenilin and nicastrin) to produce Abeta occurred in the endosomal/lysosomal system. However, other studies showing a predominant endoplasmic reticulum localization of the gamma-secretase proteins and a neutral pH optimum of in vitro gamma-secretase assays have challenged this conclusion. We have recently identified nicastrin as a major lysosomal membrane protein. In the present work, we use Western blotting and immunogold electron microscopy to demonstrate that significant amounts of mature nicastrin, presenilin-1, and APP are co-localized with lysosomal associated membrane protein-1 (cAMP-1) in the outer membranes of lysosomes. Furthermore, we demonstrate that these membranes contain an acidic gamma-secretase activity, which is immunoprecipitable with an antibody to nicastrin. These experiments establish APP, nicastrin, and presenilin-1 as resident lysosomal membrane proteins and indicate that gamma-secretase is a lysosomal protease. These data reassert the importance of the lysosomal/endosomal system in the generation of Abeta and suggest a role for lysosomes in the pathophysiology of AD.
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Affiliation(s)
- Stephen H Pasternak
- Research Institute, The Hospital for Sick Children, University of Toronto, Toronto M5G 1X8, Canada
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40
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Meyer EL, Strutz N, Gahring LC, Rogers SW. Glutamate receptor subunit 3 is modified by site-specific limited proteolysis including cleavage by gamma-secretase. J Biol Chem 2003; 278:23786-96. [PMID: 12700243 DOI: 10.1074/jbc.m301360200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ionotropic glutamate receptor (GluR) expression and function is regulated through multiple pre- and post-translational mechanisms. We find that limited proteolytic cleavage of GluR3 at two distinct sites generates stable GluR3 short forms that are glycosylated and found in association with other full-length GluRs in the mouse brain and cultured primary neurons. A combination of mutagenesis and transfection into HEK293 cells revealed cleavage by a gamma-secretase-like activity within the membrane-localized re-entry loop at or near the leucine-glycine pair (amino acids 585-586, GluR3sbeta) and a second site within a proline-rich PEST-like sequence in the first cytoplasmic loop (Asp570-Pro571, GluR3salpha). Generation of the prominent GluR3salpha form was effectively abolished in the mutant, GluR3D570A, but inhibitors of lysosomes, the proteasome, caspases, or calpains had no effect. The possible impact of cleavage on receptor function was suggested when the co-expression of the GluR3P571Stop mutant (creating GluR3salpha) co-assembled with other GluR subunits and decreased receptor function in Xenopus oocytes. In transiently transfected HEK293 cells, co-expression of GluR3salpha alters the relative association between GluR1 and GluR3 during assembly, and the presence of the novel C-terminal proline-rich domain of GluR3salpha imparts lateral membrane mobility to GluR complexes. These results suggest that limited proteolysis is another post-translational mechanism through which functional diversity and specialization between closely related GluR subunits is accomplished.
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Affiliation(s)
- Erin L Meyer
- Salt Lake City Veteran's Affairs Geriatrics Research, Education and Clinical Center, University of Utah, Salt Lake City, Utah 84132, USA
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41
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Pigino G, Morfini G, Pelsman A, Mattson MP, Brady ST, Busciglio J. Alzheimer's presenilin 1 mutations impair kinesin-based axonal transport. J Neurosci 2003; 23:4499-508. [PMID: 12805290 PMCID: PMC6740780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
Abstract
Several lines of evidence indicate that alterations in axonal transport play a critical role in Alzheimer's disease (AD) neuropathology, but the molecular mechanisms that control this process are not understood fully. Recent work indicates that presenilin 1 (PS1) interacts with glycogen synthase kinase 3beta (GSK3beta). In vivo, GSK3beta phosphorylates kinesin light chains (KLC) and causes the release of kinesin-I from membrane-bound organelles (MBOs), leading to a reduction in kinesin-I driven motility (Morfini et al., 2002b). To characterize a potential role for PS1 in the regulation of kinesin-based axonal transport, we used PS1-/- and PS1 knock-inM146V (KIM146V) mice and cultured cells. We show that relative levels of GSK3beta activity were increased in cells either in the presence of mutant PS1 or in the absence of PS1 (PS1-/-). Concomitant with increased GSK3beta activity, relative levels of KLC phosphorylation were increased, and the amount of kinesin-I bound to MBOs was reduced. Consistent with a deficit in kinesin-I-mediated fast axonal transport, densities of synaptophysin- and syntaxin-I-containing vesicles and mitochondria were reduced in neuritic processes of KIM146V hippocampal neurons. Similarly, we found reduced levels of PS1, amyloid precursor protein, and synaptophysin in sciatic nerves of KIM146V mice. Thus PS1 appears to modulate GSK3beta activity and the release of kinesin-I from MBOs at sites of vesicle delivery and membrane insertion. These findings suggest that mutations in PS1 may compromise neuronal function by affecting GSK-3 activity and kinesin-I-based motility.
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Affiliation(s)
- Gustavo Pigino
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut 06030, USA
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42
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Asaki C, Usuda N, Nakazawa A, Kametani K, Suzuki T. Localization of translational components at the ultramicroscopic level at postsynaptic sites of the rat brain. Brain Res 2003; 972:168-76. [PMID: 12711090 DOI: 10.1016/s0006-8993(03)02523-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We investigated the localization of components of translational machinery and their regulators in the postsynaptic region. We examined several components, especially those involved in translational regulation: components of (1) MAPK-Mnk-eIF4E, (2) PI3-kinase-PDK-Akt/PKB-FRAP/mTOR-PHAS/4EBP, (3) p70S6K-S6 ribosomal protein and (4) eEF2 kinase/CaMKIII-eEF2 pathways. Western blotting detected all the components examined in the synaptic fractions, and their differential localization to the synaptic subcompartments: initiation or elongation factors, except for eIF5, were detected predominantly in the dendritic lipid raft fraction, which contained ER marker proteins. In contrast, most of their regulatory kinases were distributed to both the postsynaptic density (PSD) and the dendritic lipid raft fractions, or enriched in the former fraction. Localization of eIF4E at synaptic sites was further examined immunohistochemically at the electron microscopic level. The eIF-4E-immunoreactivity was localized to the postsynaptic sites, especially to the microvesicle-like structures underneath the postsynaptic membrane in the spine, some of which were localized in close proximity to PSD. These results suggest that the postsynaptic local translational system, in at least four major regulatory pathways, is similar to those in the perinuclear one, and that it takes place, at least partly, immediately beneath the postsynaptic membrane. The results also suggest the presence of ER-associated type of translational machinery at the postsynaptic sites.
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Affiliation(s)
- Chie Asaki
- Department of Neuroplasticity, Research Center on Aging and Adaptation, Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621, Japan
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43
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Herreman A, Van Gassen G, Bentahir M, Nyabi O, Craessaerts K, Mueller U, Annaert W, De Strooper B. gamma-Secretase activity requires the presenilin-dependent trafficking of nicastrin through the Golgi apparatus but not its complex glycosylation. J Cell Sci 2003; 116:1127-36. [PMID: 12584255 DOI: 10.1242/jcs.00292] [Citation(s) in RCA: 165] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nicastrin and presenilin are two major components of the gamma-secretase complex, which executes the intramembrane proteolysis of type I integral membrane proteins such as the amyloid precursor protein (APP) and Notch. Nicastrin is synthesized in fibroblasts and neurons as an endoglycosidase-H-sensitive glycosylated precursor protein (immature nicastrin) and is then modified by complex glycosylation in the Golgi apparatus and by sialylation in the trans-Golgi network (mature nicastrin). These modifications are not observed with exogenously overexpressed nicastrin. Under normal cell culture conditions, only mature nicastrin is expressed at the cell surface and binds to the presenilin heterodimers. Mature nicastrin has a half-life of more than 24 hours. In the absence of presenilin 1 and 2, nicastrin remains entirely endoglycosidase H sensitive, is retained in the endoplasmic reticulum and is slowly degraded. Single presenilin 1 or presenilin 2 deficiency affects glycosylation of nicastrin to a lesser extent than the combined presenilin deficiencies, suggesting a correlation between either the transport of nicastrin out of the endoplasmic reticulum or the concomitant complex glycosylation of nicastrin, and gamma-secretase activity. However, when complex glycosylation of nicastrin was inhibited using mannosidase I inhibitors, gamma-secretase cleavage of APP or Notch was not inhibited and the immature nicastrin still associates with presenilin and appears at the cell surface. Complex glycosylation of nicastrin is therefore not needed for gamma-secretase activity. Because the trafficking of nicastrin to the Golgi apparatus is dependent on presenilins, our data point to a central role of presenilin in nicastrin maturation/localization, which could help to partially resolve the 'spatial paradox'.
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Affiliation(s)
- An Herreman
- Laboratory for Neuronal Cell Biology, Center for Human Genetics, Gasthuisberg/KULeuven and Flanders Interuniversity Institute for Biotechnology (VIB), Herestraat 49, 3000 Leuven, Belgium
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44
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Abstract
A remarkable rise in life expectancy during the past century has made Alzheimer's disease (AD) the most common form of progressive cognitive failure in humans. Compositional analyses of the classical brain lesions, the senile (amyloid) plaques and neurofibrillary tangles, preceded and has guided the search for genetic alterations. Four genes have been unequivocally implicated in inherited forms of AD, and mutations or polymorphisms in these genes cause excessive cerebral accumulation of the amyloid beta-protein and subsequent neuronal and glial pathology in brain regions important for memory and cognition. This understanding of the genotype-to-phenotype conversions of familial AD has led to the development of pharmacological strategies to lower amyloid beta-protein levels as a way of treating or preventing all forms of the disease.
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Affiliation(s)
- Dennis J Selkoe
- Center for Neurologic Diseases, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
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45
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Papp H, Pakaski M, Kasa P. Presenilin-1 and the amyloid precursor protein are transported bidirectionally in the sciatic nerve of adult rat. Neurochem Int 2002; 41:429-35. [PMID: 12213230 DOI: 10.1016/s0197-0186(02)00014-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The amyloid precursor protein (APP) and presenilin-1 (PS-1) are not only of importance for the normal functioning of the various neurons, but also play central roles in the pathogenesis of Alzheimer's disease (AD). Through the use of immunohistochemical and Western blot techniques, the bidirectional axonal transport of these proteins has been demonstrated in the sciatic nerve of adult rat. Double-ligation of the sciatic nerve for 6, 12 or 24h was observed to cause a progressive accumulation of the 45kDa presenilin-1 holoprotein and APPs with molecular masses of 116 and 94kDa on both sites of the ligature. It is concluded that the functions of presenilin-1 and APPs are not restricted to the neuronal perikarya: they may carry information in both directions, from the cell body to the axon terminals and vice versa.
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Affiliation(s)
- H Papp
- Department of Psychiatry, Alzheimer's Disease Research Centre, University of Szeged, Somogyi B. ut 4, H-6720 Szeged, Hungary
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46
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Abstract
Presenilins are mutated in most cases of autosomal dominant inherited forms of early onset Alzheimer's disease and such mutations are known to sensitize cells to apoptotic stimuli in vitro. Previous studies show that presenilins are primarily located in the endoplasmatic reticulum and cell membranes. Here we report, based on immunoblot analysis and immunoelectron microscopy studies, that PS1 is also located in mitochondrial membranes. For these studies we used tissue sections and subcellular fractions of rat brain and liver. Immunogold labeling of sections show that PS1 is predominantly located in the inner membrane of mitochondria. The function of PS1 in mitochondrial membranes is presently unknown. PS1 mutations may make cells more vulnerable to apoptotic stimuli due to dysfunction of this protein at the mitochondrial level.
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Affiliation(s)
- Maria Ankarcrona
- Karolinska Institutet, Neurotec, KASPAC, Novum, 5th floor, S-141 57 Huddinge, Sweden.
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47
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Kimura N, Nakamura SI, Honda T, Takashima A, Nakayama H, Ono F, Sakakibara I, Doi K, Kawamura S, Yoshikawa Y. Age-related changes in the localization of presenilin-1 in cynomolgus monkey brain. Brain Res 2001; 922:30-41. [PMID: 11730699 DOI: 10.1016/s0006-8993(01)03146-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Age-related changes in PS-1 localization were examined in the brains of 22 cynomolgus monkeys ranging in age from embryonic day 87 to 35 years. In embryonic monkey brains, anti-PS-1 antibody N12, which recognizes the PS-1 N-terminal fragment (Ntf) and holo protein, stained immature neuronal cells. In juvenile monkeys, N12 stained large pyramidal neurons, cerebral neocortical neurons, and cerebellar Purkinje's cells. Cytoplasmic staining of these cells was granular in appearance. In aged monkeys, N12 stained neurons in all layers of the neocortex. In contrast, regardless of the age of the animals examined, M5, an anti-PS-1 antibody that specifically recognizes only the PS-1 C-terminal fragment (Ctf), stained neurons in all layers of the neocortex and neurons in the cerebellum. M5 also stained neuropil and white matter, and in aged monkeys, M5 stained swollen neurites of mature senile plaques. Age-related changes in PS-1 expression were further examined using Western blot analysis of mitochondrial, myelin, microsomal, nuclear, synaptosomal, and cytosol fractions isolated from 10 monkey brains ranging in age from embryonic day 87 to 32 years. In all brains, Ntf and Ctf were expressed most abundantly in the microsome fraction. The amount of PS-1 in the nuclear fraction dramatically increased with age. We conclude that the transport of PS-1 diminished with age and that PS-1 fragments accumulated in endoplasmic reticulum (ER) associated with the nuclear membrane.
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Affiliation(s)
- N Kimura
- Department of Biomedical Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
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48
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Kim SH, Leem JY, Lah JJ, Slunt HH, Levey AI, Thinakaran G, Sisodia SS. Multiple effects of aspartate mutant presenilin 1 on the processing and trafficking of amyloid precursor protein. J Biol Chem 2001; 276:43343-50. [PMID: 11564743 DOI: 10.1074/jbc.m108245200] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PS1 deficiency and expression of PS1 with substitutions of two conserved transmembrane aspartate residues ("PS1 aspartate variants") leads to the reduction of Abeta peptide secretion and the accumulation of amyloid precursor protein (APP) C-terminal fragments. To define the nature of the "dominant negative" effect of the PS1 aspartate variants, we stably expressed PS1 harboring aspartate to alanine substitutions at codons 257 (D257A) or 385 (D385A), singly or in combination (D257A/D385A), in mouse neuroblastoma, N2a cells. Expression of the PS1 aspartate variants resulted in marked accumulation of intracellular and cell surface APP C-terminal fragments. While expression of the D385A PS1 variant reduced the levels of secreted Abeta peptides, we now show that neither the PS1 D257A nor D257A/D385A variants impair Abeta production. Surprisingly, the stability of both immature and mature forms of APP is dramatically elevated in cells expressing PS1 aspartate variants, commensurate with an increase in the cell surface levels of APP. These findings lead us to conclude that the stability and trafficking of APP can be profoundly modulated by coexpression of PS1 with mutations at aspartate 257 and aspartate 385.
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Affiliation(s)
- S H Kim
- Department of Neurobiology, The University of Chicago, Chicago, Illinois 60637, USA
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Dirami G, Ravindranath N, Achi MV, Dym M. Expression of Notch pathway components in spermatogonia and Sertoli cells of neonatal mice. JOURNAL OF ANDROLOGY 2001; 22:944-52. [PMID: 11700858 DOI: 10.1002/j.1939-4640.2001.tb03434.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Members of the Notch gene family have been shown to play an important role in the control of cell fate in many developmental systems. We hypothesized that the fate of the male germ line stem cells may also be mediated through the Notch signaling pathway. We therefore sought to determine whether the components of the Notch pathway are expressed in the mouse testis. Western blot analysis revealed the expression of three Notch receptors (Notch 1, Notch 2, and Notch 3), Notch ligands (Jagged 1, Jagged 2, and Delta 1), and presenilin 1 (PS1) in neonatal mouse testis. We then examined their cellular localization by immunohistochemical analysis of cocultures of spermatogonia and Sertoli cells. The 3 Notch receptors were found to be expressed in spermatogonia. Sertoli cells expressed only Notch 2 receptor. Among the Notch ligands, Delta 1 and Jagged 1 were localized exclusively in spermatogonia and Sertoli cells, respectively. PS1 was apparent in both spermatogonia and Sertoli cells. The presence of Notch receptors and Notch ligands in spermatogonia and Sertoli cells indicates that these cells are capable of responding to and eliciting Notch signaling during the process of spermatogenesis. Key words: Cell fate, delta, jagged, presenilin, spermatogenesis.
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MESH Headings
- Animals
- Animals, Newborn
- Blotting, Western
- Cell Culture Techniques/methods
- Cells, Cultured
- Gene Expression Regulation, Developmental
- Male
- Membrane Proteins/analysis
- Membrane Proteins/genetics
- Mice
- Mice, Inbred BALB C
- Presenilin-1
- Proto-Oncogene Proteins/analysis
- Proto-Oncogene Proteins/genetics
- Receptor, Notch1
- Receptor, Notch2
- Receptor, Notch4
- Receptors, Cell Surface/genetics
- Receptors, Notch
- Sertoli Cells/cytology
- Sertoli Cells/physiology
- Spermatogenesis/genetics
- Testis/physiology
- Transcription Factors
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Affiliation(s)
- G Dirami
- Department of Cell Biology, Georgetown University Medical Center, Washington, DC 20007, USA
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Tarabal O, Calderó J, Lladó J, Oppenheim RW, Esquerda JE. Long-lasting aberrant tubulovesicular membrane inclusions accumulate in developing motoneurons after a sublethal excitotoxic insult: a possible model for neuronal pathology in neurodegenerative disease. J Neurosci 2001; 21:8072-81. [PMID: 11588180 PMCID: PMC6763851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
We have previously shown that chronic treatment of chick embryos [from embryonic day 5 (E5) to E9] with NMDA rescues spinal cord motoneurons (MNs) from programmed cell death. In this situation, MNs exhibit a reduced vulnerability to acute excitotoxic lesions and downregulate NMDA and AMPA-kainate receptors. Here, we report that this treatment results in long-lasting sublethal structural changes in MNs. In Nissl-stained sections from the spinal cord of NMDA-treated embryos, MNs display an area adjacent to an eccentrically positioned nucleus in which basophilia is excluded. Ultrastructurally, MNs accumulate tubulovesicular structures surrounded by Golgi stacks. Thiamine pyrophosphatase but not acid phosphatase was detected inside the tubulovesicular structures, which are resistant to disruption by brefeldin A or monensin. Immunocytochemistry reveals changes in the content and distribution of calcitonin gene-related peptide, the KDEL receptor, the early endosomal marker EEA1, and the recycling endosome marker Rab11, indicating that a dysfunction in membrane trafficking and protein sorting occurs in these MNs. FM1-43, a marker of the endocytic pathway, strongly accumulates in MNs from isolated spinal cords after chronic NMDA treatment. Changes in the distribution of cystatin C and presenilin-1 and an accumulation of amyloid precursor protein and beta-amyloid product were also observed in NMDA-treated MNs. None of these alterations involve an interruption of MN-target (muscle) connections, as detected by the retrograde tracing of MNs with cholera toxin B subunit. These results demonstrate that chronic NMDA treatment induces severe changes in the motoneuronal endomembrane system that may be related to some neuropathological alterations described in human MN disease.
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Affiliation(s)
- O Tarabal
- Unitat de Neurobiologia Cellular, Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, Universitat de Lleida, E25198 Lleida, Catalonia, Spain
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